Sound-emitting device



Oct 27, 1925- V v 1,559,158

' J. H. BUTCHER ET AL SOUND EMITT-ING DEVICE Filed De c. 11, 1923 2 Sheets-Sheet 1 Fig.2. v 29 Inventors John HButcher, Arthur? Yo ping MQEQ ZQ "Their Att own e y Oct. 27 1925 Q 1,559,158

- J H. BUTCHER ET AL SOUND EMITTING DEVICE Filed Dec. 11, 1925 2 Sheets-Sheet 2 Inventbrs John HButcher; Arthur" F? Yo LAWS Their Attorney Patented Oct. 27, 1925.

UNITED STATES 1,559,158 PATENT-OFFICE,

JOHN HENRY BUTCHER, or RUGBY, AND ARTHUR rnmaosn YOUNG, E Klimt-f wom'n, ENGLAND,'ASSIGNORS 'ro GENERAL nmc'rmzc COMPANY, 41 coaronn'non OF NEW YORK.

SOUND-EMITTiNG DEVICE.

Application filed December 1 1, 1925. Serial ms. 579,974.

To all whom it may concern:

Be it known that 'we, JOHN HENRY BUTCHER and ARTHUR Pnnvmosn YOUNG, subjects of the King of Great Britain, residing, respectively, atTti'igby and at Kenilworth, in the county of Warwick, England, have invented certain new and useful Improvements in Sound-Emitting Devices, of which the following is a specification.

This invention relates to sound transmitters or emitters, such as telephone receivers or loud speakers, for use in the reception of wireless or line telephony. It relates particularly to the type wherein a moving ele ment, associated with a diaphragm "or its equivalent, is set in vibration by means of the fluctuations of flux derived from the magnetic circuit in response to oscillating currents received by the apparatus, although it is not. limited to this type. I

According to the presentinvcntion, a magnetic circuit and actuating coil are as? sociated with a .hollow casing or'barrel' which may be formed like. aiviolin bell and v provided w th brackets 12"carry1 ng clampwhich functions as the diaphragm oft e instrument. Preferablythe' magnetic circuit is arran ed within the hollowcasing, and

the movmg' element is connected to opposite sides of the casing in a manner to trans mit its vibrations to the saidcasihge. The casing may be-of any material capable of vibrating at audible frequencies, but a was ing constructed of box-wood is preferred- The invention also consists in arranging 3 a diaphragm on each side of'the magnetic circuit in place of the hollowcasi-ng afore' mentioned, said diaphragmsbeing actuated in a manner similar to the way in which the hollow casing is actuated. Various typeset ma netic circuit may beemployed with the 1101 ow casing or double diaphragms but the preferred constructions are set ont diargrammatically in the accompanying draw in s. g

a magnetic circuit comprising a number of curved or straight magnets arranged sub va hollow casing wit v '15, The. reed 22 is consequently supporte In another construction there is provided Another. construction comprises a sub thereof. A cooperating magnetic disc'or reed is disposed adjacent-to the pole faces in such away that magnetic attraction or re- 00 .pulsion. causes it to vibrate substantially. as

awhole, i. e. in a rigid. manner...

The novel. features which we believe to be characteristic of our invention are set-forth, with particularity in the appendedfclaims, the invention itself howeverwill best be understood by referenceto the following description-taken in connection with the accompanying drawin s in which Fig. 1 shows a magnetic circuit arranged within; Fi s. 2 and 3 show alternative magnetic circuitsgFig. 4 shows another 'construction-' of magnetic circuit for use I with a circular magnetic member; 5 illustrates'a diaphragm and Fig; .6is an end section thereof, and Fig.7 shows a construction .in which the diaphragm is actuated di'-'- rectly by the magnetic flux.

Referring now to'Fig. 1', a framell is 6 mg bolts-l3 arranged to engagewith the ends l l of abarrel-shaped-tubular casing 15. The ends 14 may 'beformed of a ri '(1 material such as-aluminum, but'thetubu ar orQ tion 15 is formed of, any material whic is both resilient and able to vibrate at audible frequencies. The ma etic circuit comprises two structures 1 consisting of soft iron laminations arranged substantially in; the form ofa rectangular C with their. opens ings facing towards one another. The'actuating coils l8 aremounted upon the outside limbs as shown and connected by leads 19 to terminals 21.- -Within the air 'aps in the structures 17 is arranged amova le reed 2:? which. is permanently magnetized, and angle-shapedrcds 23 connect the-ends of the reed to opposite sides of the tubular 'cas'in through the two connecting rods'23, and no other-pivot-is therefore necessary, althou h' secured the enddiscs 14'. In order that the shalt be symmetrically disposed with respect to the poles oi the structures 17, the ends of the connect ng rods are screw 110 threaded and cooperate with milled nuts provided with screw-threads externally which engage with the threaded bosses 26 upon the tubular casing 15. Consequenlly rotation of one or both of the nuts 25 will permit the adjustment of the reed until is centrally disposed with respect to the air gaps. In order to facilitate making this adjustment, a longitudinal window may he provided in one or both of the sides of the tubular member 15, said window being formed of a resilient material, such as mica, and this will add to the resiliency of the casing.

The electric coils 18 are so wound and connected as to produce similar polarities in the poles 0t each structure which are on the same side oi the reed. Consequently, when an oscillating current flows through the coils it will produce a variable iiuX, which, owing to the permanent magnetization of the reed, will cause the latter to vibrate, these vibrations being transmitted through the connecting rods 28 to the casing 15. It should be noticed that a passageway is provided in each structure to take the connecting rods.

Fig. 2 shows a substantially similar construction of magneticcircuit, but one in which each at the structures is permanently magnetized. For instance, the pole pieces 27 may themselves be, permanent magnets of a material such as cobalt steel, or the main core 28 may itself be a permanent magnet. In either case the polarity of the magnets is such as to produce similar polarities in the pole pieces adjacent the air-gaps on the same side foil": the reed. The poles adjacent the air-gaps are nurrlced N. and S. to demonstrate this. The actuating coils 18 are disposed between the structiu'es 1? around the reed 22. In this case the reed may be polarized or unpolarised, and We have shown the connecting rods 23 joining the ends of the reed to two diaphragms 29 arranged one on each side of the apparatus, these dim phragms taking the place of the tubular casing shown in Fig. l. A transformer for regulating the current to the requisite amount is indicated at 31.

With this arrangement, the diaphragms may be connected up to sound pipes in a manner to ensure an accumulative efi'eet, a sound horn or the like being provided to emit the combined sound. it will be obvious, however, that instead of using the diaphragrns 29, this magnetic circuit can be employed in the construction of Fig. 1 in stead oi the one there shown. i

Fig. 3 illustrates another construction comprising permanent magnets 32 whose ends are connected by soft: iron. yoires 33 to central poles 34 extending towards one another to form an air any nonmagnetic material, Such as alumin- Brackets 35 of him, are dovetailed into the yokes and cut away in the center as shown. An unpolarized reed 22 has its ends carried by these brackets 35 and around the reed and towards the ends thereof are wound the actuating coils 18. Although we have shown these coils as being mounted directly upon the reed, they may if preferred be carried by the brackets The polarity of the magnets is such as to produce opposite poles on each side of the air gap and the coils themselves are rerersely connected so that an oscillating current in the coils will produce a consequent pole, alternately north and south, at the center of the reed. This will cause the reed to be attracted alternately by the pole pieces 34, the reed being sufficiently resilient to permit of this. Connecting rods 23 are secured at one end to the reed and arranged to pass up longitudinal holes in the pole pieces being connected at their outer ends to the tubular casing 15 or alternately to diaphragms after the manner indicated with reference to Fig. 2

It will be observed that this construction differs from the constructions in Figs. 1 and 2 for the following reasons: In the constructions of Figs. 1 and 2 an oscillating current in the actuating'cnils 18 causes the reed to vibrate about its mid point, which in turn causes the upper and lower sides of the casing 15 or the diaphragms 29, as the case may be, to be drawn towards one another at the same time and then repelled from one another. In the construction shown in Fig. 3, however, an oscillatingcurrent will cause the upper side of the casing to be drawn towards the structure whilst the lower side is being repelled therefrom. and vice versa.

Another form of magnetic circuit is illustrated in Fig. 4 comprising a number of curved bar magnets 36 arranged substantially in the form of a broken circle. On one side of each magnet are fixed pole pieces 37 adapted to carry the actuating coils (not shown in this figure). A cooperating magnetic disc'is provided adiacent the faces of the pole pieces, and the actuating coils are so connected as to cause the attraction of the magnetic disc towards and away from the pole pieces. A similar structure may be used cooperating with a magnetic disc carried upon one side of the hollow casing.

A suitable non-magnetic diaphragm for use with apparatus as above described and sound emitters or transmitters in general.

may be constructed as shown in Figs. 5 and 6 comprising a thin disc of fabric 38 impregnated with a synthetic resin and having annular corrugations of synthetic resin 39 mounted on each side of the fabric disc.

Fig. '7 depicts a construction of ni'agnetic circuit wherein the coils 18 are disposed upon laminated pole pieces 41 etc. permanent magnet 42. A diaphragm or magnetic member 43 formed of rigid material is mounted so as to have a small air-ga between each face of the pole pieces an the diaphragm itself. The member 43 is arranged so that the pole pieces are ad'acent its periphery and is carried by V-s apedclamps 44 formed of impregnated fabric. Owing to the position of the pole pieces relatively to the member 43 oscillating current in the coils 18 causes the member 43 to vibrate as a whole.

\Vhat we claim as new and desire to secure by Letters Patent of the United States,

1. The combination in a sound emitting device of a hollow casing which serves as a diaphragm and an actuating mechanism enclosed in said'casing and attached to opposite sides thereof.

2. The combination in a sound emitting device of a hollow casing of non-magnetic material which serves as a dia hragm and.

an actuating mechanism enclose in said casing and attached to opposite sides thereof.

3'. The combination in a sound emitting within said casing, comprising a magnetic structure, actuating windings and a movable armature which is attached to opposite sides of said casing.

5. The combination in a sound emitting device of a hollow tubular casing of nonmagnetic material, having its ends closed, and the sides of which serve as a dia-- phragm, and an actuating mechanism enclosed in said casing and attachedto opposite sides thereof, said actuating mechanism being supported by the ends of said casing.

6. The combination in a sound emitting device of a hollow tubular casing of nonmagnetic material having its ends. closed, and the sides of which serve as a diaphragm, and an actuating mechanism enclosed in said casing and attached'to opposite sides thereof, said actuating mechanism being supported by the ends of saidicasing and being adapted to simultaneously produce vibratlon 0 both sides of the casing.

7. A sound emitting device comprising a hollow casing having end portions, actuat ing mechanism mounted on said end portions, and a movable armature cooperating with said actuating mechanism and opposite portions of said casing.

In witness whereof, we have hereunto set our hands this nineteenth day of November, 1923.

JOHN HENRY BUTCHER. ARTHUR PRIMROSE YOUNG. 

